Corneal prosthesis and method of penetrating keratoplasty

ABSTRACT

A method of implanting the prosthesis is disclosed. The method includes forming an opening in a host tissue of an eye. The method also includes forming a perimeter of a corneal graft. The method also includes forming a first passageway through the host tissue and a second passageway through the corneal graft. The first passageway and the second passageway can have the same diameter relative to an optic axis of the eye. The method also includes aligning the first passageway and the second passageway whereby the first passageway and the second passageway are in communication with one another. The method also includes positioning a body in the first passageway and the second passageway.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.16/572,531, for a CORNEAL PROSTHESIS AND METHOD OF PENETRATINGKERATOPLASTY, filed Sep. 16, 2019, which claimed the benefit of U.S.Provisional Patent Application Ser. No. 62/731,260 for a METHOD FORCREATING DONOR AND HOST INTERFACE FOR CORNEAL TRANSPLANTATION, filed onSep. 14, 2018, which is hereby incorporated by reference in itsentirety.

BACKGROUND 1. Field

The present disclosure relates to a prosthesis for the eye and moreparticularly to an implant for use in penetrating keratoplasty.

2. Description of Related Prior Art

The cornea is the clear front surface of the eyeball and is responsiblefor the majority of the convex focusing power of the human eye. Thecornea is subject to many diseases and injuries which can reduce itsoptical clarity and therefore replacement of the central cornea withthat of a deceased donor is a common and necessary medical procedure.Such a procedure is known as corneal transplantation or penetratingkeratoplasty. Some forms of corneal transplantation may only requirereplacement of a partial layer of the host cornea as in lamellarkeratoplasty or endothelial keratoplasty. However, for many diseaseconditions full thickness corneal transplantation remains the onlypractical surgical option. Corneal transplantation is a very challengingsurgery because optimal mechanical alignment of the donor tissue withthe host is important to minimize inflammation that can cause a failureof the donor tissue. The interface between the host and donor tissuemust have proper anatomical alignment to minimize wound disruption andinduced astigmatism.

U.S. Pat. No. 8,273,121 discloses a Process of use of a device forcornea transplantation. The invention of the '121 patent is a surgicalinstrument (1) used in ophthalmology, which allows a penetrating orlamellar cornea transplant without the use of suture. It comprises a setof arc segments interconnected by a small diameter polypropylene wire(2), which goes through the internal body structure of each segment. Thefirst arc segment (3), also called the segment guide, is an arc of160-330 degrees with a circular cross-section and a rounded edge. Thesecond arc segment (4), also called the main segment, is an arc of270-360 degrees, and has a horizontal or oblique cross-sectiontangential to the surface of the cornea, or a circular cross-section.The third arc segment (5), also called the secondary segment, has athickness or cross-section greater than that of the main segment.

U.S. Pat. No. 8,388,608 discloses a Method and implant for attachment ofthe transplanted cornea. The transplanted cornea attachment method ofthe '608 patent in eye microsurgery and the implant for attachingtransplanted corneas, both donor and artificial, without the use ofsutures consisting in the cutting of a fragment of the donor tissue (2)and, subsequently, the incision of the corresponding fragment (1) in therecipient tissue (3) so that the donated fragment (2) and the recipientincision (1) have teeth that interlock with each other, and the circularincision (5) in the stroma of the donor and recipient corneal stromawhich is less in diameter in the donor tissue and more in diameter inthe recipient tissue wherein the fastening implant (4) is subsequentlyinserted.

U.S. Pub. No. 2006/0100612 discloses a Laser-based device fornon-mechanical, three-dimensional trepanation during cornea transplants.The laser-based device for non-mechanical, three-dimensional trepanationduring cornea transplants comprises a computer-assisted control andregulation unit (4) provided with at least one control computer (5, 6,7) and at least one display unit (8, 9), as well as a laser source (2)for generating a working laser beam (3) as well as a multi-sensorprocessing head (1) integrated into which are: an axial beam positioningsystem (11) into which the working laser beam (3) can be coupled, afocal point tracking unit (12) for the z-position displacement of thefocal point (13) of the working laser beam (3) an x-y-scanner unit (14,15) for the x and y-position displacement of the working laser beam (3),an eye position sensor unit (23, 24, 35, 36) for detection of theposition of the eye, and a plasma sensor unit (16, 25) for detection ofthe plasma glow that occurs during the cornea trepanation.

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

SUMMARY

A method of implanting the prosthesis is disclosed. The method includesforming an opening in a host tissue of an eye. The method also includesforming a perimeter of a corneal graft. The method also includes forminga first passageway through the host tissue that extends annularly aboutan optic axis of the eye. The method also includes forming a secondpassageway through the corneal graft that extends annularly about anaxis of the corneal graft that is substantially collinear with the opticaxis of the eye when the corneal graft is finally positioned in the eye.The first passageway and the second passageway can have the samediameter relative to the optic axis. The method also includes aligningthe first passageway and the second passageway whereby the firstpassageway and the second passageway are in communication with oneanother. The method also includes positioning a body in the firstpassageway and the second passageway.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description set forth below references the followingdrawings:

FIG. 1 is a front view of a prosthesis according to an exemplaryembodiment of the present disclosure, wherein the prosthesis is in anopen configuration;

FIG. 2 is a front view of the prosthesis shown in FIG. 1 in a closedconfiguration;

FIG. 3 is a side view of the prosthesis shown in FIG. 1 in a closedconfiguration;

FIG. 4 is a side view of a prosthesis according to another exemplaryembodiment of the present disclosure, wherein the prosthesis is in aclosed configuration;

FIG. 5 is a front view of a portion of a host cornea and a cornealgraft;

FIG. 6 is a cross-section through section lines 6-6 in FIG. 5;

FIG. 7 is a cross-section through section lines 7-7 in FIG. 5;

FIG. 8 is a front view of a portion of another host cornea;

FIG. 9 is a sectional view of the portion shown in FIG. 8;

FIG. 10 is a front view of another corneal graft;

FIG. 11 is a sectional view of the corneal graft shown in FIG. 10;

FIG. 12 is a front view of a portion of another host cornea and anothercorneal graft;

FIG. 13 is a sectional view of the host cornea and the corneal prothesisshown in FIG. 12;

FIG. 14 is a sectional view of a portion of another host cornea andanother corneal prothesis;

FIG. 15 is a second sectional view of the portion of the host cornea andthe corneal prothesis shown in FIG. 14;

FIG. 16 is a front view of a prosthesis according to another embodimentof the present disclosure;

FIG. 17 is a side view of the prosthesis shown in FIG. 16;

FIG. 18 is a front view of a portion of a host cornea and a cornealgraft according to another embodiment of the present disclosure;

FIG. 19 is a cross-section through section lines 19-19 in FIG. 18;

FIG. 20 is a cross-section through section lines 20-20 in FIG. 18;

FIG. 21 is a front view of a portion of a host cornea and a cornealgraft according to another embodiment of the present disclosure;

FIG. 22 is a magnified and perspective view of a portion of thestructures shown in FIG. 21;

FIG. 23 is a front view of a portion of a host cornea and a cornealgraft;

FIG. 24 is a second front view of the portion of the host cornea and thecorneal graft shown in FIG. 23 with both structures shown in phantom anda prosthesis which was not visible in FIG. 23 shown in solid line and isassociated with a first exemplary method provided by the presentdisclosure;

FIG. 25A-25D illustrate a series of images associated with a secondexemplary method provided by the present disclosure; and

FIG. 26A-26D illustrate a series of images associated with a thirdexemplary method provided by the present disclosure.

DETAILED DESCRIPTION

A plurality of different embodiments of the present disclosure is shownin the Figures of the application. Similar features are shown in thevarious embodiments of the present disclosure. Similar features acrossdifferent embodiments have been numbered with a common reference numeraland have been differentiated by an alphabetic suffix. Similar featuresin a particular embodiment have been numbered with a common two-digit,base reference numeral and have been differentiated by a differentleading numeral. Also, to enhance consistency, the structures in anyparticular drawing share the same alphabetic suffix even if a particularfeature is shown in less than all embodiments. Similar features arestructured similarly, operate similarly, and/or have the same functionunless otherwise indicated by the drawings or this specification.Furthermore, particular features of one embodiment can replacecorresponding features in another embodiment or can supplement otherembodiments unless otherwise indicated by the drawings or thisspecification.

The present disclosure, as demonstrated by the exemplary embodimentsdescribed below, can provide a prosthesis for use in penetratingkeratoplasty that obviates the need for sutures. Referring now to FIGS.1-3, an exemplary prosthesis 10 is configured to be implanted in acornea of an eye to interconnect host tissue with a corneal graft. Theexemplary prosthesis 10 includes a body 12 extending between a first end14 and a second end 16. The exemplary body 12 defines a section ofmaximum width between the exemplary first end 14 and the exemplarysecond end 16. In the exemplary embodiment, the body 12 has a maximumwidth over most of its length and the section of maximum width isreferenced at 18.

The exemplary body 12 narrows from the exemplary maximum width 18 at theexemplary first end 14 and converges to a first tip 20. The exemplaryfirst tip 20 is hastate-shaped. The exemplary body 12 also narrows fromthe exemplary maximum width 18 at the exemplary second end 16 andconverges to a second tip 22. The exemplary tips 20, 22 are at oppositeends of the body 12. The inner and outer edges of the body 12 can bemodified from what is shown in the Figures such that one or both of theedges of the body 12 are nonplanar (not flat in a plane ofcross-section) and that such edges can fit into complementary grooves ina tunnel or trench formed in host tissue 44 or the corneal graft 54. Forexample, the edges can include lips that protrude anteriorly and orposteriorly to allow for better fixation and easier passage through thetunnel, slit or trench. These ends can also be fashioned like bulbs incross-section to allow for firmer fixation of the cornea.

The exemplary prosthesis 10 also includes a slit 24 defined in theexemplary body 12 at the exemplary first end 14. The exemplary slit 24has a width, referenced at 26. A portion of the exemplary body 12,between the exemplary second tip 22 and the exemplary section 18 ofmaximum width, has a width, referenced at 28. The width 26 is greaterthan width 28. As a result, the portion of the exemplary body 12 betweenthe exemplary second tip 22 and the exemplary section 18 of maximumwidth is receivable in the exemplary slit 24. In the exemplaryembodiment shown in FIG. 1, this portion of the exemplary body isdefined between the second tip 22 and the location that width 28 isreferenced at 30. The portion 30 is the part of the exemplary body 12that can fit in the slit 24.

The exemplary prosthesis 10 also includes a plurality of fingersincluding first and second sets of fingers 32, 34 projecting laterallyaway from the portion 30 of the exemplary body 12 between the exemplarysecond tip 22 and the exemplary section 18 of maximum width. Theexemplary first and second sets of fingers 32, 34 project from oppositesides of the exemplary body 12. First and second individual fingers 36,38 of the exemplary first and second sets of fingers 32, 34 respectivelyproject laterally away from the portion 30 of the exemplary body 12between the exemplary second tip 22 and the exemplary section 18 ofmaximum width. The exemplary first and second fingers 36, 38 mirroringone another across a central axis 40 of the portion 30 of the exemplarybody 12 between the exemplary second tip 22 and the exemplary section 18of maximum width. The fingers of the exemplary first and second sets offingers 32, 34 project obliquely to the portion 30. In otherembodiments, the fingers could extend perpendicular to the body 12. Thefingers of the exemplary first and second sets of fingers 32, 34 areelastically deformable when the portion 30 of the exemplary body 12between the exemplary second tip 22 and the exemplary section 18 ofmaximum width is passing through the exemplary slit 24. A finger canthus bend during passage of the portion 30 through the slit 24 andreturn to form once the finger has passed through the slit 24.

The exemplary prosthesis 10 is reconfigurable between an open orunlatched configuration and a close or latched configuration. FIG. 1 isa front view of the exemplary prosthesis 10 in the open configuration.The front view is from the same perspective as looking into the eyeafter the exemplary prosthesis 10 has been implanted. To reconfigure theexemplary prosthesis 10 from the open configuration to the closedconfiguration, the second end 22 is inserted in the slit 24 and,further, at least some part of the length of the portion 30 is drawnthrough the slit 24. The exemplary prosthesis 10 remains in the closedconfiguration through the cooperative interaction between the fingersand the slit 24. FIG. 2 is a front view of the exemplary prosthesis 10shown in the closed configuration. FIG. 3 is a side view of theexemplary prosthesis 10 in the closed configuration. In the exemplaryembodiment, the fingers 36, 38 passed through the slit 24, elasticallyrecovered, and inhibit the portion 30 from retreating out of the slit24. Also, in the exemplary embodiment, the portion 30 has been trimmedafter passing into the slit 24. The trimmed end of the portion 30 isreferenced at 42.

Referring now to FIG. 4, an exemplary prosthesis 10 a is configured tobe implanted in a cornea of an eye to interconnect host tissue with acorneal graft. The exemplary prosthesis 10 a includes a body 12 aextending between a first end 14 a and a second end (similar to secondend 16). An exemplary first tip 20 a at the first end 14 a is pointed,shaped as a “less than” mathematical symbol. The exemplary body 12 adefines a section of maximum width between the exemplary first end 14 aand the exemplary second end. In the exemplary embodiment, the body 12has a maximum width over most of its length and the section of maximumwidth is referenced at 18 a. The exemplary prosthesis 10 a is configuredto be cylindrical when implanted, while the exemplary prosthesis 10 isconfigured to be frustoconical when implanted.

The present disclosure also provides a method of implanting theexemplary prosthesis 10. The method includes forming an opening in thehost tissue of the eye. Referring now to FIGS. 5-7, exemplary hosttissue is referenced at 44 and an exemplary opening is referenced at 46.The exemplary opening 46 in the exemplary host tissue 44 has been formedto include a first plurality of flaps in the exemplary host tissue 44.Two of the flaps are referenced at 48, 148 and the flaps are positionedabout an optic axis 50 of the eye. The flaps extend toward the opticaxis 50.

The method also includes forming a perimeter of the corneal graft tocorrespond to the exemplary opening 46 in the exemplary host tissue 44such that the exemplary corneal graft 54 is receivable in the exemplaryopening 46. Referring still to FIGS. 5-7, an exemplary perimeter isreferenced at 52 and an exemplary corneal graft is referenced at 54. Theexemplary perimeter 52 has been formed to include a second plurality offlaps in the exemplary corneal graft 54 positioned about the optic axis.Two of the flaps are referenced at 56, 156 and the flaps are positionedabout the optic axis 50 of the eye. The flaps extend away from the opticaxis 50 when the exemplary corneal graft 54 is finally positioned in theeye. In the embodiment reflected in FIGS. 5-7, the exemplary cornealgraft 54 is fully received in the exemplary opening 46. As shown inFIGS. 6 and 7, the edges of the exemplary corneal graft 54 are flushwith the edges of the exemplary opening 46 and the edges of the hosttissue 44.

The method also includes forming a first passageway through theexemplary host tissue 44 that extends annularly about the optic axis 50of the eye. An exemplary first passageway is referenced at 58 in FIG. 6.The exemplary first passageway 58 comprises discontinuous tunnelportions, each extending through one of the first plurality of flaps ofthe host tissue 44. The method also includes forming a second passagewaythrough the exemplary corneal graft 54 that extends annularly about anaxis of the exemplary corneal graft 54 that is substantially collinearwith the optic axis 50 of the eye when the exemplary corneal graft 54 isfinally positioned in the eye. An exemplary second passageway isreferenced at 60 in FIG. 7. The exemplary second passageway 60 includesdiscontinuous tunnel portions, each extending through one of the secondplurality of flaps. The passageways 58, 60 can be formed with afemtosecond laser.

The method also includes aligning the first passageway and the secondpassageway whereby the first passageway and the second passageway are incommunication with one another. In the exemplary embodiment, this can beaccomplished by inserting the exemplary corneal graft 54 into exemplaryopening 46 of the exemplary host tissue 44 such that the first pluralityof flaps and the second plurality of flaps circumferentially andalternatingly overlap about the optic axis when the exemplary cornealgraft 54 is finally positioned in the eye. The portions of the secondpassageway 60 in the second plurality of flaps line up with the portionsof the first passageway 58 in the first plurality of flaps.

The method also includes positioning the exemplary body 12 concurrentlyin the first passageway 58 and the second passageway 60. In theexemplary embodiment, the body 12 can be woven into the first and secondplurality of flaps. The first tip 20 be successively directed througheach tunnel portion in each flap until the body 12 extends through everytunnel portion.

The method also includes directing the exemplary second tip 22 throughthe exemplary slit 24. The exemplary second tip 22 can be directedthrough the exemplary slit 24 until at least one of the first set offingers and at least one of the second set of fingers pass through theexemplary slit 24. The length of the portion 30 that is drawn throughthe slit 24 is chosen as desired, such as to optimize the tightness ortautness of the interconnection between the host tissue 44 and thecorneal graft 54. Thus, in some operating environments, it may bedesirable that a plurality of the first set of fingers and a pluralityof the second set of fingers pass through the exemplary slit 24. In theexemplary embodiment, the portion 30 is directed through the slit 24after the body 12 is positioned in the first and second passageways 58,60 and after the first and second passageways 58, 60 are aligned.

FIGS. 8-11 correspond to exemplary method of implanting the exemplaryprosthesis 10 a. The method includes forming an opening in the hosttissue of the eye. As referenced in FIGS. 8 and 9, an exemplary opening46 a has been formed in the exemplary host tissue 44 a. Dashed lines 62a and 64 a reference the outer and inner profiles of the portion of thehost tissue 44 a that has been removed.

The method also includes forming a perimeter of the corneal graft. Asshown in FIGS. 8 and 9, an exemplary perimeter is referenced at 52 a andan exemplary corneal graft is referenced at 54 a. In the embodimentreflected in FIGS. 5-7, the exemplary corneal graft 54 is fully receivedin the exemplary opening 46. As will be described, in the embodimentreflected in FIGS. 8-11, the exemplary corneal graft 54 a is partiallyreceived in the exemplary opening 46 a.

The method also includes forming a first passageway through theexemplary host tissue 44 a that extends annularly about the optic axis50 a of the eye. An exemplary first passageway is referenced at 58 a inFIGS. 8 and 9. The exemplary first passageway 58 a comprises continuoustrench formed into an external surface of the exemplary host tissue 44a.

The method also includes forming a second passageway through theexemplary corneal graft 54 a that extends annularly about an axis of theexemplary corneal graft 54 a that is substantially collinear with theoptic axis 50 a of the eye when the exemplary corneal graft 54 a isfinally positioned in the eye. The position of the optic axis 50 arelative to the corneal graft 54 a when the exemplary corneal graft 54 ais finally positioned in the eye is shown in dashed line in FIG. 11. Anexemplary second passageway is referenced at 60 a in FIGS. 10 and 11.The exemplary second passageway 60 a includes a continuous trench formedinto an external surface of the exemplary corneal graft 54 a. Thepassageways 58 a, 60 a can be formed with a femtosecond laser.

The method also includes aligning the first passageway and the secondpassageway whereby the first passageway and the second passageway are incommunication with one another. In the exemplary embodiment, this can beaccomplished by first locating the exemplary body 12 a fully in thefirst passageway 58 a. The exemplary corneal graft 54 can then be movedthrough the opening 46 a and progressively adjusted to slip the secondpassageway 60 a over the exemplary body 12 a, which projects out of thefirst passageway 58 a along the axis 50 a.

The method also includes directing the exemplary second tip of the body12 a through the exemplary slit 24 a. The exemplary second tip can bedirected through the exemplary slit 24 a until at least one of the firstset of fingers and at least one of the second set of fingers passthrough the exemplary slit 24 a. The length of the portion 30 a that isdrawn through the slit 24 a is chosen as desired, such as to optimizethe tightness or tautness of the interconnection between the host tissue44 a and the corneal graft 54 a. Thus, in some operating environments,it may be desirable that a plurality of the first set of fingers and aplurality of the second set of fingers pass through the exemplary slit24 a. It is noted that the line 66 a in FIG. 9 represents, inexaggerated form, the outer surface of the corneal graft 54 a aftercompletion of the method. It is noted that swollen tissue in the eye canenhance the interconnection between the host tissue 44 a and the graft54 a.

FIGS. 12 and 13 correspond to exemplary method of implanting theexemplary prosthesis 10. An exemplary opening 46 b has been formed inexemplary host tissue 44 b to include a first undercut 68 b extendingcircumferentially about an optic axis 50 b. An undercut is a structuralfeature in which material has been cut away from the underside of astructure so as to leave an overhanging portion in relief. An exemplaryperimeter 52 b has been formed in a corneal graft 54 b to include asecond undercut 70 b extending circumferentially about the optic axis 50b. First and second passageways have also been formed, similar to thepassageways 58, 60, but cylindrically-shaped rather than frustoconical.The undercuts 68 b, 70 b are received in one another when the exemplarycorneal graft 54 a is finally positioned in the eye. The undercuts 68 b,70 b can be formed with a femtosecond laser.

FIGS. 14 and 15 correspond to exemplary method of implanting theexemplary prosthesis 10 or the exemplary prosthesis 10 a. FIG. 14 is across-section taken in a similar plane to the plane shown in FIG. 6 andFIG. 15 is a cross-section taken in a similar plane to the plane shownin FIG. 7. The flaps shown in the embodiment of FIGS. 5-7 have beenfurther modified such the flaps circumferentially and alternatinglyoverlap about the optic axis and also overlap along the optic axis whenthe exemplary corneal graft 54 c is finally positioned in the eye. Hosttissue 44 c includes flaps 48 c and 148 c. Each of the flaps 48 c, 148 chas been further shaped to include outer and inner portions by removinga middle portion. The empty middle portions have been filled by portions72 c, 172 c of a corneal graft 54 c. Similarly, flaps 56 c, 156 c of thecorneal graft 54 c has been further shaped to include outer and innerportions by removing a middle portion. The empty middle portions of thecorneal graft 54 c have been filled by portions 74 c, 174 c of the hosttissue 44 c.

In one or more embodiments of the present disclosure, the prosthesis mayinclude fenestration (one or more perforations in the structure), asshown in FIG. 3 in phantom and referenced at 76. Fenestration would bebeneficial both to permit corneal healing at the interface and allowdiffusion of oxygen to the central cornea. Fenestration in theprosthesis can be subject to postoperative modulation by appliedelectromagnetic energy (such as a laser) to change tension in shapewithin the band and adjust for refractive properties of the cornea oncethe stable refractive outcome can be assessed postoperatively. In one ormore embodiments of the present disclosure, the prosthesis can includeelements visible on the outer surface that can be subject topostoperative modulation by applied electromagnetic energy to alter theshape of the prosthesis and thus change tension within the band.Examples are referenced in FIGS. 1 and 2 at 78. This can be done toadjust for refractive properties of the cornea once the stablerefractive outcome can be assessed postoperatively. FIGS. 16 and 17disclose an embodiment of the present disclosure in which a continuousprosthesis 10 d is frustoconical and includes fenestrations 76 d andelements 78 d to be subjected to laser energy.

In embodiments of the present disclosure in which the prosthesis iscircular, it may be desirable that the shape of the graft (also known asthe “donor button”) can be undulating or petaloid, as shown in FIG. 5.If the shape of the donor button is circular, as might be necessitatedif replacing a failed circular graft, or if inserting akeratoprosthesis, then the prosthesis itself can be continuous and/ornoncircular in order to pass through both recipient tissue and foreignimplant/transplant. Such a shape may be a circular zigzag (such as aStar of David) or a circle with an undulating circumference (a wavy,circular perimeter). If the prosthesis is to be threaded through atunnel, a rigid, discontinuous circle can be desirable. If it is to beinserted into a trench incision (as shown in FIGS. 8-11) then either acircular zigzag or a circle with an undulating circumference can be adesirable shape.

In various embodiments of the present disclosure, the prosthesis canslip into the trench in the donor tissue so that the corneal epitheliumwill go back over it and that the prosthesis in the recipient tissuewould not protrude beyond the inner endothelial cell layer and thus notdisrupt the normal physiology of the cornea and anterior chamber. Sincethe thickness of the cornea at this junction would be approximately fivehundred μm, a trench depth of about two hundred and fifty μm in both theunderside of the recipient and top surface of the donor tissue wouldseem desirable and thus limit the vertical height of the prosthesis toabout two hundred μm or less. A prosthesis of one hundred μm thicknessshould have ample strength. However, materials such as titanium or otherbiocompatible could provide both the rigidity and strength to a smallerprosthesis in order to be handled and placed without damage. There arealso biocompatible aerogels which have enormous strength with limitedbrittleness.

In one or more embodiments of the present disclosure, the method offorming circumferential suture tracks through the host and/or donortissue can include using a femtosecond laser. The tracks may be ofmultiple sets of varying diameter. Although the present disclosureprovides methods and structures tending to minimize the need forsutures, pre-placement of suture tracks in such a manner that makessuture placement faster and more accurate and use less suture materialand the less traumatic needle can be included with various embodimentsof the present disclosure. It is noted that only one knot may be neededto be tied each set of sutures at a particular diameter.

In one or more embodiments of the present disclosure, a prosthesis cancontain a depot of slow-release medication such as steroids andantibiotic to facilitate healing, especially in the fenestrationsdescribed above. Another medication that would be useful would bepreparations such as vitamin A which are activated by ultraviolet lightto promote a process known as collagen cross-linking which hasbeneficial effects in many corneal diseases and strengthens the cornea.The drug depot reservoir function can be desirable for a) collagencross-linking, b) immunosuppressants to prevent rejection, and c)antibiotics to prevent infection.

FIGS. 18-20 illustrate another embodiment of the present disclosure.Host tissue 44 e has received a corneal graft 54 e and the interface hasbeen shaped with interlocking flaps or petals. A prosthesis 10 e ispassing through a discontinuous tunnel 58 e in the host tissue 44 e andis received in a discontinuous trench 60 e formed in the corneal graft54 e. The appearance of the prosthesis 10 e in FIG. 18 shows thediscontinuous tunnel 58 e (a first passageway) and the discontinuoustrench 60 e (a second passageway) have the same diameter relative to anoptic axis 50 e. Thus, the flaps of the corneal graft 54 e are drapedover the portions of the prosthesis 10 e that are exposed betweenadjacent flaps of the host tissue 44 e. As shown by FIG. 20, thediscontinuous tunnel 58 e in the host tissue 44 e has been formed toinclude a laterally extending gap (referenced at 80 e) to the tunnel 58e in order to allow the prosthesis 10 e to be continuous and inserted inthe host tissue 44 e more easily. Thus, a prosthesis according to thepresent disclosure can either be fully closed prior to implantation(i.e. constructed as a continuous loop) as shown in FIGS. 18-20 or canbe closed after positioning as exemplified by the embodiment shown inFIG. 1.

FIGS. 19 and 20 also illustrate another embodiment of a prosthesis ofthe present disclosure. The prosthesis 10 e is generally circular orellipsoid in cross-section and includes an outer layer 82 e and an innerlayer 84 e. The layers 82 e, 84 e are formed from different materials.The material used for layer 82 e can be responsive to laser energy of afirst wavelength, to expand or contract. The material used for layer 84e can be responsive to laser energy of a second wavelength differentfrom the first wavelength, to expand or contract. The material used forlayer 82 e can be unresponsive to laser energy of the second wavelengthand the material used for layer 84 e can be unresponsive to laser energyof a first wavelength. Thus, one of the layers 82 e, 84 e could bemodified with laser energy to shrink and thereby tighten theinterconnection between the host tissue 44 e and the corneal graft 54 ewhile the other could be modified with laser energy to expand andthereby loosen the interconnection between the host tissue 44 e and thecorneal graft 54 e.

FIGS. 21 and 22 illustrate another embodiment of the present disclosure.Host tissue 44 f has received a corneal graft 54 f and the interface hasbeen shaped with interlocking flaps or petals. It is noted that anarbitrary outer boundary of the host tissue 44 f is referenced at 86 fIn FIG. 21, patterns of suture tracks have been formed by a femtosecondlaser in the host tissue 44 f and the corneal graft 54 f. These suturetracks are illustrated as dots and an outer pattern includes suturetracks such as referenced at 88 f and an inner pattern includes suturetracks such as referenced at 90 f Sutures can be used in conjunctionwith a prosthesis. FIG. 22 shows sutures 92 f, 192 f extending throughand between suture tracks. FIG. 22 also shows a portion of the pathtaken by each suture 92 f, 192 f, with the sutures 92 f, 192 frepresented in phantom when passing below the surface. It can bedesirable to complete and tie the outer suture 192 f first for stabilityand then adjust the tightness of the inner suture 92 f as desired.Including the sutures 92 f, 192 f can be desirable to inhibitastigmatism. It can be desirable to reduce the distance between thesuture and the corneal periphery in order to reduce corneal inflammationand neovascularization.

The present disclosure also provides various methods for using aprosthesis in combination with a suture. FIG. 23 is a front view of aportion of a host cornea 44 g and a corneal graft 54 g. FIG. 24 is asecond front view of the portion of the host cornea 44 g and the cornealgraft 54 g shown in FIG. 23 with both structures shown in phantom and aprosthesis 10 g which was not visible in FIG. 23 shown in solid line.The prosthesis 10 g is associated with a first exemplary method providedby the present disclosure.

The exemplary prosthesis/body 10 g is discontinuous about an optic axis50 g and extends between a leading edge 94 g and a trailing edge 96 g. Afirst suture 98 g is attached to the leading edge 94 g of the body 10 gand a second suture 100 g is attached to the trailing edge 96 g of thebody 10 g. The exemplary suture 98 g is shown forming a loop. The suture98 g can be drawn through a first passageway in the host cornea 44 g anda second passageway corneal graft 54 g with the body 10 g as the body 10g is positioned in those passageways. When the body 10 g is positionedin both passageways, the suture 98 g can be drawn or pulled out of thepassageways and exposed for use. Next, the suture 98 g and the secondsuture 100 g can be tied together and thereby bring the leading edge 94g and trailing edge 96 g together.

FIG. 25A-25D illustrate a series of images associated with a secondexemplary method provided by the present disclosure. A suture 102 g isattached to the leading edge 94 g and also to the trailing edge 96 g ofthe body 10 g. The suture 102 g can be drawn through a first passagewayin the host cornea 44 g and a second passageway corneal graft 54 g withthe body 10 g as the body 10 g is being positioned in those passageways,as shown in FIG. 25A. FIG. 25A also shows a portion 104 g of the suture102 g exposed and not in the passageways. Next, a second portion 106 gof the suture 102 g can be drawn or pulled out of the passageways andexposed for use as shown in FIG. 25B. Then, the first portion 104 g thesuture 102 g and the second portion 106 g of the suture 102 g can betied together, as shown in FIG. 25C. The extraneous portions of thesuture 102 g can then be removed, as shown in FIG. 25C.

FIG. 26A-26D illustrate a series of images associated with a thirdexemplary method provided by the present disclosure. An exemplary suture108 g is attached to the leading edge 94 g but not to the trailing edge96 g of the body 10 g. The suture 108 g can be drawn through a firstpassageway in the host cornea 44 g and a second passageway corneal graft54 g with the body 10 g as the body 10 g is being positioned in thosepassageways. FIG. 26A also shows a trailing end portion 110 g of thesuture 108 g exposed and not in the passageways. FIG. 26a also shows asecond portion 112 g of the suture 108 g has been drawn or pulled out ofthe passageways and exposed for use. FIG. 26B shows the suture 108 gseparated from the body 10 g after being drawn through the passageways.FIG. 26C shows the body 10 g removed from the passageways after thesuture 108 g has been drawn through the passageways. FIG. 26D shows theportions 110 g and 112 g having been tied together and extraneousportions of the suture 108 g removed.

In one or more embodiments of the present disclosure, a prosthesis/bodythat is discontinuous can be altered after being positioned in thepassageways. A discontinuous prosthesis/body can at least partiallyoverlap itself over a length after being positioned in the passageways.One example of overlap is shown in FIG. 4. Externally-generated energy,such as with a laser directed at the overlap, can be applied at aposition along the length of overlap to weld portions of theprosthesis/body together and convert the prosthesis/body fromdiscontinuous to continuous.

In one or more embodiments of the present disclosure, a prosthesis/bodythat is discontinuous or continuous can be altered after beingpositioned in the passageways. After being positioned, theprosthesis/body can define a circumferential tension or loop tension.Externally-generated energy, such as with a laser directed at someposition along the prosthesis/body, can be applied to change thecircumferential tension. The laser can be directed at one or more pointssuch as points 78 shown in FIGS. 1 and 2. The prosthesis/body can beformed from different kinds of material so that the application ofenergy could increase the circumferential tension or decrease thecircumferential tension. A particular embodiment of a prosthesis/bodycould be formed from more than one kind of material so that a firstportion of the prosthesis/body could be altered to increase thecircumferential tension and a second portion of the prosthesis/bodycould be altered to decrease the circumferential tension.

In one or more embodiments of the present disclosure, a prosthesis/bodythat is discontinuous or continuous can be altered in other ways afterbeing positioned in the passageways. A prosthesis/body in one or moreembodiments can extend along a central longitudinal axis and defines awidth transverse to the central longitudinal axis. Exemplary width 18 isreferenced in FIG. 1. Externally-generated energy, such as with a laserdirected at some position along the prosthesis/body, can be applied tochange the width at that position. The laser can be directed at one ormore points such as points 78 shown in FIGS. 1 and 2. Theprosthesis/body can be formed from different kinds of material so thatthe application of energy could increase or decrease the width. Aparticular embodiment of a prosthesis/body could be formed from morethan one kind of material so that a first portion of the prosthesis/bodycould be altered to increase the width and a second portion of theprosthesis/body could be altered to decrease the width.

In one or more embodiments of the present disclosure, a continuousversion of the prosthesis that can be placed in trench-like passageways(fashioned in the corneal stroma with openings to the external surface)that connects the host and donor tissues, with the assembly of theprosthesis and donor tissue held in close apposition to the host tissueby virtue of intraocular pressure. The disclosure of FIGS. 11, 18 and 19described versions of such embodiments and it is noted that allcombinations of passageway configurations shown in the other Figures ofthe present disclosure could be applied in such embodiments.

While the present disclosure has been described with reference to anexemplary embodiment, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the presentdisclosure. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the presentdisclosure without departing from the essential scope thereof.Therefore, it is intended that the present disclosure not be limited tothe particular embodiment disclosed as the best mode contemplated forcarrying out this present disclosure, but that the present disclosurewill include all embodiments falling within the scope of the appendedclaims. The right to claim elements and/or sub-combinations that aredisclosed herein is hereby unconditionally reserved. The use of the word“can” in this document is not an assertion that the subject precedingthe word is unimportant or unnecessary or “not critical” relative toanything else in this document. The word “can” is used herein in apositive and affirming sense and no other motive should be presumed.More than one “invention” may be disclosed in the present disclosure; an“invention” is defined by the content of a patent claim and not by thecontent of a detailed description of an embodiment of an invention.

What is claimed is:
 1. A method of implanting the prosthesis comprising:forming an opening in a host tissue of an eye; forming a perimeter of acorneal graft; forming a first passageway through the host tissue thatextends annularly about an optic axis of the eye; forming a secondpassageway through the corneal graft that extends annularly about anaxis of the corneal graft that is substantially collinear with the opticaxis of the eye when said corneal graft is finally positioned in theeye, the first passageway and the second passageway having the samediameter relative to the optic axis; aligning the first passageway andthe second passageway whereby the first passageway and the secondpassageway are in communication with one another; and positioning a bodyin the first passageway and the second passageway.
 2. The method ofclaim 1 wherein: said forming the opening in the host tissue of the eyeis further defined as forming the opening to include a first pluralityof flaps in the host tissue positioned about the optic axis andextending toward the optic axis; said forming the perimeter of thecorneal graft is further defined as forming the perimeter to include asecond plurality of flaps in the corneal graft positioned about theoptic axis and extending away from the optic axis when the corneal graftis finally positioned in the eye; and said method further comprises:arranging the corneal graft and the host tissue relative to one anothersuch that the first plurality of flaps and the second plurality of flapscircumferentially and alternatingly overlap about the optic axis whenthe corneal graft is finally positioned in the eye.
 3. The method ofclaim 1 wherein: said forming the opening in the host tissue of the eyeis further defined as forming the opening to include a first pluralityof flaps in the host tissue positioned about the optic axis andextending toward the optic axis; said forming the perimeter of thecorneal graft is further defined as forming the perimeter to include asecond plurality of flaps in the corneal graft positioned about theoptic axis and extending away from the optic axis when the corneal graftis finally positioned in the eye; and said method further comprises:arranging the corneal graft and the host tissue relative to one anothersuch that the first plurality of flaps and the second plurality of flapscircumferentially and alternatingly overlap about the optic axis andalso overlap along the optic axis when the corneal graft is finallypositioned in the eye.
 4. The method of claim 1 wherein: said formingthe opening in the host tissue of the eye is further defined as formingthe opening to include a first undercut in the host tissue extendingcircumferentially about the optic axis; said forming the perimeter ofthe corneal graft is further defined as forming the perimeter to includea second undercut in the corneal graft extending circumferentially aboutthe optic axis when the corneal graft is finally positioned in the eye;and said method further comprises: arranging the corneal graft and thehost tissue relative to one another such that the first undercut and thesecond undercut are received in one another when the corneal graft isfinally positioned in the eye.
 5. The method of claim 1 wherein: saidforming the first passageway is further defined as forming the firstpassageway to be continuous in the host tissue; and said forming thesecond passageway is further defined as forming the second passageway tobe continuous in the corneal graft.
 6. The method of claim 1 whereinsaid positioning is further defined as: positioning the body in thefirst passageway and the second passageway wherein the body iscontinuous about the optic axis.
 7. The method of claim 1 furthercomprising: drawing a suture through the first passageway and the secondpassageway with the body during said positioning.
 8. The method of claim7 wherein said positioning is further defined as: positioning the bodyin the first passageway and the second passageway wherein the body isdiscontinuous about the optic axis and extends between a leading edgeand a trailing edge, and the suture is attached to at least the leadingedge of the body.
 9. The method of claim 8 wherein said drawing isfurther defined as: drawing the suture through the first passageway andthe second passageway with the body during said positioning, wherein asecond suture is attached to the trailing edge.
 10. The method of claim9 further comprising: tying the suture and the second suture togetherafter said drawing and thereby bring the leading edge and trailing edgetogether.
 11. The method of claim 8 wherein said drawing is furtherdefined as: drawing the suture through the first passageway and thesecond passageway with the body during said positioning as the suture isalso attached to the trailing edge.
 12. The method of claim 11 furthercomprising: tying a first portion the suture and a second portion of thesuture together after said drawing and thereby bring the leading edgeand trailing edge together.
 13. The method of claim 8 furthercomprising: separating the suture from the body after said drawing;removing the body from the first passageway and the second passagewayafter said drawing; and tying a first portion the suture and a secondportion of the suture together after said separating.
 14. The method ofclaim 7 further comprising: separating the suture from the body aftersaid drawing; and removing the body from the first passageway and thesecond passageway after said separating.
 15. The method of claim 1:wherein said positioning is further defined as positioning the body inthe first passageway and the second passageway wherein the body isdiscontinuous about the optic axis and extends between a leading edgeand a trailing edge and at least partially overlaps itself over alength; and further comprising applying, after said positioning,externally-generated energy to the length to convert the body fromdiscontinuous to continuous.
 16. The method of claim 1 furthercomprising: changing a circumferential tension defined in the body byapplying, after said positioning, externally-generated energy to thebody.
 17. The method of claim 1 wherein said body extends along acentral longitudinal axis and defines a width transverse to the centrallongitudinal axis and further comprising: changing the width of the bodyat a position along the central longitudinal axis by applying, aftersaid positioning, externally-generated energy to the body at theposition.